Pressure fluid motor



Nov. 30, 1937. M, Q HUFFMAN 2,100,904

PRESSURE FLUID MOTOR Filed Seplt. l2, 1932 2 Sheets-Sheet l hmmm y MA'Mw/lm.

Nov. 30, 1937.

M. c. HUFFMAN 2,100,904

PRES SUBE FLUID MOTOR Filed sept. 12, 1932 2'sheetS-sheet 2 Patented Nov. 30, 1937 2,100,904 PRESSURE. FLUID Mofrolty Mervin Chester HuHman, Claremont, N. H., assignor to Sullivan Machinery Company, a corporation of Massachusetts Application Septemberl2, 1932, Serial No. 632,728

11 Claims.

This invention relates to pressure iiuid motors and more particularly to improvements in the uid distribution means of a pressure fluid motor of the type particularly adapted to use in 5 hammer rock drills. Y

An object of this invention is to provide an improved pressure fluid motor. Another object is to provide improved fluid distribution means for a pressure fluid motor. A further object is l to provide an improved pressure uid motor of the hammer type particularly adapted to use in rock drills. A further object is to provide in a motor of the above character an improved valve mechanism for controlling the supply of presl sure fluid to the piston chamber in an improved manner. These and other objects of the invention will, however, hereinafter more fully appear in the course of the following description and as more particularly pointed out in the appended claims.

In the accompanying drawings there is shown for purposes of illustration one form and a modification thereof which the invention may lassume in practice.

In these drawings,-

Fig. l is a central, longitudinally extending, vertical sectional view of the preferred illustrative embodiment of the invention.

Fig. 2 is a view similar to Fig. l showing the iluid distributing valve and motor piston in Va diiferent position. v

Fig. 3 is a front end elevational View of one of the valve chest elements per se.

Fig. 4 is an elevational view of the fluid dis- ;3 tributing valve per se.

Fig. 5 is a view similar to Fig. l showing the parts in a hole blowing position.

Fig. 6 is a transverse vertical sectional view taken substantially on line 6-8 of Figs. l and 5.

Fig. '7 is a fragmentary horizontal sectional view taken substantially on line 'l-l of Fig. 6.

Fig. 8 is a detail sectional view taken substantially on line 8-8 of Fig. 6.

Fig. 9 is an enlarged detail sectional view show- 5 ing the distributing valve and its associated passage means.

Fig. l0 is a fragmentary view similar to Fig. 5 showing a modified form of construction.

fn this illustrative embodiment of the invention there is shown a pressure fluid motor of the hammer type particularly adapted to use in rock drills comprising a motor cylinder I having a piston chamber 2 containing a reciprocable hammer piston 3. The hammer piston is pro- 55 vided with an integral cylindrical extension or striking bar 4 projecting forwardly through Ya bushing 5 carried within a front buffer ring 6 herein forming the front head of the motor." Rotatably mounted within a chuck housing 1, as clearly shown in Fig. 5, is a chuck sleeve 8 carrying a chuck bushing 9. Supported within the chuck bushing is the shank I0 of a usual hollow drill steel, the shank I0 projecting rearwardly within a chamber I I formed in the chuck sleeve in a position to receive the impact blows of the piston striking bar 4 in the marmer well underf stood in the art. Secured to the cylinder I `at the rear end thereof is a back head I2, and this back head and the front head 6, the chuck housing 'I and the cylinder are held in assembled relation by any suitable means, Yherein by usual side rods i3, I3, as shown in Fig. 6. As is usual in rock drilling tools, the drill steel is rotated by the hammer piston as it is percussively actuated thereby, and this rotation means consists of a usual ratchet Aand pawl device I4 including a stationary ratchet ring I5 and an oscillatory pawl carrier I6, herein formed integral with a rifle bar I'I herein arranged at the reanend of the motor cylinder in axial alinement therewith and extending forwardly `within the piston in engagement with a rifle nut I8 secured within the piston, as shown in Fig. l. As the motor piston moves forwardly, the pawls of the pawl carrier slip over the ratchet teeth, thereby permitting an unimpeded forward stroke of the motor piston, and upon reversal of the motor piston the pawls hold the rifle bar against rotation, and as a result the spiral grooves thereof engaging the spiral lugs of `the rifle nut cause the hammer .piston to rotate as it moves rearwardly. Rotative movement 'of the hammer piston is transmitted to the drill steel through straight grooves I9 formed externally on the striking bar 4 and engaging straight lugs 2G formed internally on the chuck sleeve 8 which in turn carries the steel supporting chuck'bushing. It will thus beseen that upon .,everyretraction stroke of the hammer piston a slight rotative movement is imparted to the rdrill steel.

Now referring to the improved fluid distribution means and more particularly to theimproved valve mechanism,.it will be noted that formed within the rearward portion of the motor cylinder and vin alinement with the piston chamber is an enlarged bore 2I whichk receives the ratchet ring I5, and interposed between the ratchet ring and ashoulder 22 formed on the cylinder are cooperating valverchest elements 23 and 24. The elements 23 and 24 are herein arranged in face to face abutting relation and are clamped in position against the shoulder 22 by the head block I2 engaging the ratchet ring I5. In the present construction, formed in the valve chest element 23 and surrounding the rifle bar I 1 is an annular valve chamber 25 having reciprocably mounted therein an annular flat disc or plate valve 25. This valve is provided withy a central bore 21 and is slidably mounted upon and guided by the cylindrical portion of the rifle bar I1 in the manner shown. Formed on the valve chest elements 23 and 24 respectively at the opposite sidesY of the valve chamber are concentric annular seats 28, 29, 30 and 3|, the seats 28, 29 arranged at the opposite sides of an annular groove or recess 32 formed in the element 23, while the seats 39, 3| are arranged at the opposite sides of an annular groove or recess 33 formed in the element 24. Also arranged concentric with the grooves 32, 33 and formed in the valve chest elements 23, 24 respectively, f are inner annular grooves or recesses34 and 35. Also formed on the element 24 concentric with the grooves 33, 35 is an outer annular groove or recess 36. In the present construction the valve chamber is of slightly greater diameter than the valve element 28 to provide a restricted annular passage past the valve through the valve chamber as clearly shown in Fig. 9. This particular valve design permits close regulation of the Vflow of pressure fluid to the opposite ends of the piston chamber. The ow past the valve tothe rear end of the piston chamber is regulated by the valve throwing space between the forward face of thevvalve and the front wall of the valve chamber, while the ow to the front end of the piston chamber is regulated by the clearance space about the peripheral edge of the valve. The clearance space about the peripheral edge of the valve may obviously be more or less than the throwing space between the forward face of the valve and the front wall of the valve chamber. Arranged transversely of the back head |2 is a throttle valve 31 having a. central supply chamber 38 `and radial passages 39 and 39a for connecting the chamber 38 witha supply passage 40 formed in the back head and communicating with an annular chamber .4I surrounding an annular projection 42 integral with the back head and forming a bearing for the rear end of the rie bar I1, as shown in Fig. 1'. The chamber 4I communicates through the spaces formed between the ratchet teeth of the 4ratchetfring with an annular groove or recess 43formed in the rearward face of the valve chest element 23. The recess 43 is connected by a series of longitudinal passages 44 formed in the valve chest element 23 with the annular groove 36. The central annular groove 33 formed in the rear face of the valve chest element 24 is communicable with the rear end of the piston chamber through a series of longitudinal passages 45. The outer groove 32 formed in the valve chest element 23 at the rear side of the valve chamber is communicable with the front end of the piston chamber through a pair of radial passages 4B formed in the element 23 and ports 41, longitudinal passages 48 and ports 49 Vformed in the motor cylinder. As above mentioned there are two sets ofpassages and ports 46, 41, 48, 49, butv one set being shown in Fig. 8, while the two passages 48 are clearly shown in Fig. 6. Formed in the wall of the cylinder intermediate the ends thereof is an annular piston chamber exhaust groove 50 communicable through a lateral exhaust port 5I with the atmosphere. Y

Associated with the improved fluid distribution means above described is the improved hole blowing device. Formed in a lateral boss 52 integral with the cylinder is a longitudinal bore 53 herein arranged parallel with the piston chamber, while also formed in the boss 52 parallel with the bore 53 is a bore 54. This latter bore forms a lubricant reservoir from which lubricant is supplied in an appropriate manner to the moving parts of the motor. Arranged in the bore 53 is a reciprocable plunger valve 55 having a sleeve-like body 56, and this valve when in the position shown in Fig. 5, cuts off communication between the exhaust groove 50 and the exhaust port 5I. The plunger valve is actuated in the forward direction and held closed by pressure fluid, and is returned to its inoperative or open position by a coiled spring 51 connected to a transverse pin 58 secured to the Valve and to a pin 59 secured to a cylindrical plug 60 fitting within the rear end of the bore 53. For supplying uid to the bore 53 to actuate the valve 55 there is formed in the throttle valve 31 a radial passage 6I communicating with the pressure chamber 38 in the Valve and a passage 62 formed inthe back head I2. Communicating with the passage 62 is a passage 63 formed in the ratchet ring I5, and this passagev in turn communicates with a radial passage 54 formed in the motor cylinder. The passage 64 is connected by longitudinal passage 65 and a radial passage 66 communicating with the bore 53. Communicating with the grooves 35, 36 in the valve chest element 24 through ports 61, 58 respectively is a radial passage 69 in turn communicating through passages 10, 1 I groove 12 (when the valve 5B is in its foremost or closed position), and exhaust passage 13 communicating with the atmosphere.

The groove 35 is constantly supplied with live pressure through the ports 51 and 68 and the passage 39 while the groove 34 is constantly supplied with live` pressure through passages I4 formed in the valve chest element 23 as shown in Figs. l and 3, and communicating through the ratchet ring with the chamber 4|.

In the operation of the improved iluid distribution means when theV parts are in the position shown in Fig. 1 and the throttle valve 31 is turned toV bring the passage 39 in communication with passage 4i), pressure fluid may how from the pressure chamber 38 in theV valve to the groove 4I and thence throughrthe spaces between the ratchet teeth, groover43, passages 44 to the annular groove 35. At thistime the valve 26 is held against the annular seats V23, 2S, cutting off communication between the pressure chamber 35 and the longitudinal supply passages 48 communicating with the forward end ofthe piston chamber. V Pressure uid then flows from the chamber 35 through the valve chamber past the forward face of the valve and through groove 33 and passages 45 to the rearY end of the piston chamber, the pressure fluid acting on the rear face of the hammer piston to drive the latter forwardly to effect its working stroke, i. e. to strike a blow on the shank of the drill steel. At this time the forward end of the pistonchamber is open to exhaust through groove 55 and exhaust passage 5I, and as the piston travels forwardly the groove 50 is cut off by the piston head, and upon continued forward movement a substantial compression pressure is built up by the piston withindthe forward end of the piston chamber. As the rear edge of the piston head overruns the exhaust groove 50, the rear end of the piston lchamber isv connected to exhaust through exhaust passage 5|, and as a result the pressure Within the rear end -of the piston chamber and in the groove 33 is substantially reduced. The compression pressure built up within the forward end of the pressure chamber, passages 48, 48'and groove 32 aided by the pressure fluid in'the concentric groove 311 overcomes the opposed reduced pressure in the groove 33 and the pressure fluid in groove 35, thereby throwing the valve from the positionl shown in Fig. 1 to the position shown in Fig. 2. When the parts are in the position shown in Fig. 2, the valve is held against the concentric annular seats 3l), 3l, cutting off communication between the rear end of the cylinder bore and the annular supply groove 35, and pressure fluid then flows from the groove 3S through the valve chamber past theV outer periphery of the valve, through groove 32, passages 46, ports l andpassagesV 48 and ports 49 to thev forward end of the piston` chamber, the pressure fluid acting on the forward pressure area of the piston to drive the latter rearwardly to eect its retraction stroke. At this time the pressure at the forward end of the piston chamber is connected to exhaust through groove 5@ and exhaust passage 5l, and as the piston moves rearwardly the exhaust groove 5S is overrun by the piston, and upon continued rearward movement of the piston a substantial compression pressure is built up within the rear end of the piston chamber. As the piston moves rearwardly the forward edge of the piston head overruns the groove 55, connecting the forward end of the piston chamber to exhaust, and as a result the pressure within the forward end of the piston chamber and in passages 28, 439 and groove 32 at the rear side of the valve is substantially reduced. The compression pressure in the rear end oi the piston chamber and groove S3 at the forward side of the valve aided by the pressure fluid in the groove 35 overruns the reduced pressure in the groove S2 and the pressure fluid in groove 34, and as a result the valve is thrown from the position shown in Fig. 2 to the initial position shown in Fig. l, these operations being rapidly repeated during normal operation of the motor.

If it is 'desired to eiect a hole blowing operation, that is, to supply a continuous flow of pressure fluid from the front end of the piston chamber through the rotation grooves I9 in the piston striking bar and thence through the chuck sleeve and the bore in the drill steel to the bottom of' the drill hole, the operator rotates the throttle valve 3l to the position shown in Fig. 5 to bring the passage 39a in communication with the passage 49 and passage 6| in communication with passage 62 so that without interrupting the flow of pressure uid to the distribution means, pressure fluid is supplied from the chamber 38 through port El, passages '52, 53, S4, 65, 85 to the bore 53 at the rear side of the valve 56, moving the latter forwardly from the position shown in Fig. l to the position shown in Fig. 5, thereby cutting oi communication between the exhaust groove 5i? and the exhaust passage 5l When the plunger valve 5B is in the position shown in Fig. 5, the groove 35 at the forward side of the valve is vented to atmosphere through passages 63 and l5, groove i2 in the valve and exhaust port 13, and the reduced pressure in the groove 35 at the forward side of the valve is overcome by the pressure in the groove 3?/1, thereby causing the valve to assume .the position shown in Figs. 21and 5 with the pressure fluid iiowing from the supplyV the cutting oi of the cylinder exhaust and the venting of the forward side of the valve, the valve is locked `in the position shown in Fig. 2, and as a result, the pressure in the forward end of the piston chamber retracts the hammer piston Aand holds the same immovable in its rearmost position, as shown in Fig. 5. Pressure uid then iiows continuously through passages d8, 68 to the front end of the piston chamber and thence through the grooves i9 in the piston striking bar and the chuck sleeve and through the bore in the drill steel to the bottom of the drill hole to blow the cuttings from the hole. W'hen normal drilling is to be resumed,` the throttle valve is turned into a position to vent the passageV 52 to atmosphere in a suitable manner, and as a result, the plunger valve 56 is moved rearwardly rinto its inoperative or open position by the coiled spring 5l.

In the modified form of construction shown in Fig. 9, the operation of ,the fluid distribution means and exhaust control valve is identical to that above described with the exception that in this instance the vent port '59 communicating with the groove 35 is omitted, and when the plunger valve 5t is in the position shown, that is in the hole blowing position, the endof the piston` chamber is connected to atmosphere through passages l5, "it, the groove 'i2 and the vent port 13. It will thus be evident that when the exhaust control valve is in the position shown, the rear end of the piston chamber is vented to atmosphere, and as the hammer piston moves rearwardly no compression pressure is built up within the rear end of the piston chamber to effect throwing of the valve in the rearward direction, and as a result the pressure in the valve chamber at the rear side of the valveholds Vthe valve immovable in its forward position. The hammer piston is then held retracted and the hole blown in the manner above described. Otherwise this form of the invention is identical to that above described.

As a result of this invention, it will be noted that an improved pressure fluid motor is provided having an improved valve mechanism wherein the supply of pressure fluid to the piston chamber is controlled in an improved manner resulting in a motor having more eiiiciency and a more rapid piston speed. It will further be noted that by associating with the improved fluid distribution means the improved hole blowing device, a hole blowing operation is effected in an improved manner. These and other uses and advantages of the invention will be clearly apparent to those skilled in the art.

While there is in this application specifically described one form, and a modification thereof, which the invention may assume in practice, it will be understood that this form, and modification thereof, of the same is shown for purposes of illustration and that the vinvention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims. g

What I claim as new and desire to secure by Letters Patent is: Y

l. In a pressure fluid motor, a cylinder providing a piston chamber, a piston reciprocable in said chamber, and fluid distribution means for effect-v ing reciprocation of said piston including a valve chestihaving VVa valve chamber, an annular disc valve reciprocable in said valve chamber, a pair of concentric annular recesses formed in the valve chest at one side of the valve chamber, three concentric annular recesses formed in the valve chest at the opposite side of the valve chamber. annular seats surrounding certain of said annular recesses against which the opposite facesV of the valve are adapted to seat, passage means connecting one of said pair of recesses with one end of the piston chamber, passage means connecting one of said three recesses with the opposite end of the piston chamber, and passage means for supplying pressure fluid to all of said other recesses at the opposite sides of the valve chamber, said fluid distribution means including means for conducting pressure fluid from one of said three concentric recesses to both of said recesses at the opposite sides of the valve chamber with which said first and second mentioned passage means communicate.

2; In a pressure fluid motor, a cylinder providing a piston chamber, a piston reciprocable therein, and fluid distribution means for effecting reciprocation of said piston including a valve chest arranged at the rear end of the cylinder and having a valve chamber, an annular disc valve reciprocable in said valve chamber, concentric annular grooves formed in the valve chest at opposite sides of the valve chamber, annular seats surrounding said grooves against which the oppo- -Vsite faces of the valve are engageable, a series of longitudinal passages formed in the valve chest for connecting one of the grooves at the front side of the valve with the rear end of the piston chamber, passage means for Vconnecting one of the grooves at the opposite side of the valve with the opposite end of the piston chamber, a groove surrounding the grooves at one side of the valve chamber and communicating at its inner peripheral edge directly with the outer peripheral edge of said'valve chamber, pressure uid ilowing from Ysaid groove under the control of the valve to said grooves with which said passage means communicate, and passage means for supplying pressure iiuid to said last mentioned groove.

3. In a pressure uid motor, a cylinder providing a piston chamber, a piston reciprocable therein, and uid distribution means for effecting reciprocation of said piston including a valve chest arranged at the rear end of the cylinder and having a valve chamber, an annular disc valve Y reciprocable in said valve chamber, concentric annular grooves formed in the valve chest at opposite sides of the valve chamber, annular seats surrounding said grooves against which the opposite faces of the valve are engageable, a series I longitudinal passages formed in the valve chest for connecting one of the grooves at the front side of the valve with the rear end of the piston chamber, passage means for connectingone of the grooves at the opposite side of the valve with the opposite end of the piston chamber, a fluid supply groove surrounding said concentric grooves at one side of said valve chamber and communicating with the opposite sides of said valve chamber for supplying Ypressure ud to the latter, a second fluid supply groove formed in the rear face of the valve chest, and a series of longitudinal passages formed in the valve chest for conducting pressure fluid from said second fluid supply groove to said first fluid supply groove.

4. In a pressure uid motor, a cylinder providing a piston chamber, va piston reciprocable therein, and-fluid distribution means for effecting reciprocation of said piston including a valve chest arranged vat the rear end of the cylinder andhaving a valve chamber, an annular disc valve reciprocable in said valve chamber, apair of concentric annular grooves formed in the valve chest at the rear side of the valve chamber, three concentric annular grooves form-ed in the valve chest at the front side of the valve chamber, annular seats surrounding certain of said grooves against which the opposite faces of the valve are engageable, passage means for supplying pressure uid to the inner of said grooves, passage means for connecting said outer groove of said pair and the central groove of said three with the opposite ends of the piston chamber, and passage means for supplying pressure fluid to the outer of said three grooves.

5. In a pressure fluid motor, a cylinder providing a piston chamber, a piston reciprocable therein, and fluid Vdistribution means for effecting reciprocation of said piston including a valve chest arranged at the rear end of the cylinder and having a valve chamber, an annular disc valve reciprocable in said valve chamber, a pair of concentric annular grooves formed in the'valve chest at the rear side of the valve chamber, three concentric annular grooves formed in the valve chest at the front side of the valve chamber, the outer of said threek concentric grooves communieating with the opposite sides of said valve chamber for supplying pressure fluid to the latter, annular seats surrounding certain of said grooves against which the opposite faces of the valve are engageable, passage means for supplying pres'- sure fluid to the inner of said grooves to provide a constant valve throwing pressure acting on the opposite faces of said valve, passage means for connecting said outer groove of said pair and the central groove of said three with the oppo-` site ends of the piston chamber, and passage means forsupplying pressure fluid to the outer of said three grooves, pressure fluid flowing from the outer of said three grooves under the control of the valve to the outer of said pair of grooves and to the centralgroove of said three grooves. f

6. In a pressure uid motor, a cylinder providing a piston chamber, a piston reciprocable in said piston chamber, and iiuid distribution means for eecting reciprocation of said piston including a valve chest having a valve chamber of uniform bore, an annular, iiat disc valve reciprocable in said chamber, means for guiding said valve at its inner peripheral edge, there being provided a restricted clearance about the outer peripheral edge of the valve between the valve and the valve chamber, and means for actuating said valve and conducting fluid to eifect Vpiston actuation including means forming a passage leading from oneend of said valve chamber to one end of the piston chamber, means forming a passage leading from the opposite end of said valve chamber Vto the opposite end of the piston chamber, and means for conducting piston actuating fluid to said valve chamber having communication with the latter at a point such that all the fluid flowing from said conducting means to the passage of one of said passage forming means must pass through said restricted clearance and then radially of one end of said valve while fluid pass- Ying from said conductingY means to the passage of the other of said passage forming means passes across the opposite end surface of said valve thereto. Y

7. In a pressure'fluid motor, a cylinder providing a piston chamber, a piston reciprocable in said piston chamber, and fluid distribution means for effecting reciprocation of said piston including a valve chest having a valve chamber of uni- -form bore, an annular, flat disc valve reciprocable in said chamber, means for guiding said Valve at its inner peripheral edge, there being provided a restricted clearance about the outer peripheral edge of the valve between the valve and the valve chamber, and means for actuating said valve and distributing fluid under its control, to effect piston actuation, including means forming a passage leading from one end of said valve chamber to one 'end of the piston chamber, means forming a passage leading from the opposite end of said valve chamber to the opposite end of the piston chamber, and means for conducting piston actuating fluid to said valve chamber having communication with the latter at a point such that all the fluid flowing from said conducting means to the passage of one of said passage forming means must pass through said restricted clearance and then radially of one end of said valve while fluid passing from said conducting means to the passage of the other of said passage forming means passes across the opposite end surface of said valve thereto, the area of the space about the peripheral edge of said valve being different from the valve chamber area through which pressure fluid flows past one end surface of the valve thereby to provide regulation for ow of the pressure fluid flowing to the opposite ends of said piston chamber.

8. ln a pressure fluid motor, a cylinder providing a piston chamber, a piston reciprocable in said piston chamber, and fluid distribution means for effecting reciprocation of said piston including a valve chest having a valve chamber of uniform bore, concentric annular grooves formed in each end wall of said valve chamber and having annular seats surrounding the same, an annular, flat disc valve reciprocable in said valve chamber and engageable with said seats, said valve being of Iless diameter than said valve chamber to provide a restricted clearance about the peripheral edge of said valve, means forming a passage leading from one groove at one end of said valve chamber to one end of the piston chamber, and means forming a passage leading from a groove at the other end of said valve chamber to the opposite end of said piston chamber, means for supplying fluid to the others of said grooves, and means for conducting piston actuating fluid to said valve chamber having communication with the latter at a point such that all the fluid flowing from said conducting means tc the passage of one of said passage forming means must pass through said restricted clearance, then radially of one end of said valve and through the groove communicating with the passage, while fluid passing from said conducting means to the passage of the other of said passage forming means passes across the opposite end surface of said valve and through the other groove to the passage.

9. In a pressure fluid motor, a cylinder providing a piston chamber, a piston reciprocable in said piston chamber, and fluid distribution means for effecting reciprocation of said piston including a valve chest having a valve chamber of uniform bore, concentric annular grooves formed in each end wall of said valve chamber and surrounded by annular seats, an annular, flat disc valve reciprocable in said valve chamber and engageable with said valve seats, said valve being of less diameter than said Valve 5 chamber to provide a restrictedv clearance about the peripheral edge of said valve, meansv forming a passage leading from onek of the grooves at one end of the valve chamber to one, end of said piston chamber, means` forming a passage leading from one of said grooves at the opposite end of the valve chamber to the opposite'end of the piston chamber, means for supplying pressure fluid constantly to the others of said concentric grooves, and means for conducting pis-l ton actuating fluid to said valve chamber having communication with the latter at a point such that all the fluid flowing from said conducting means to the passage, of. one of said passage forming means must pass through said restricted clearance, then radially of one end of said valve and through the groove to the passage, while fluid passing from said conducting means to the passage of the other of said passage forming means passes across .the opposite end 'surface of the valve through the groove to the passage, said valve being thrown into its opposite positions by the constant pressure in said other concentric grooves and by compression pressure built up by the piston within the opposite ends of the piston chamber and in said supply passages.

10. In a pressure fluid motor, a cylinder providing a piston chamber, a piston reciprocable therein, and fluid distribution means for effecting reciprocation of said piston including a valve chest comprising cooperating plates, a circular recess formed in the face of one of said plates, said other plate having its adjacent face abutting said face of said other plate to form the outer wall of said recess, a. flat disc valve reciprocable in said recess, the adjacent faces of said plates at the opposite ends of the valve chamber each having formed therein concentric annular grooves struck on the same radii from a common center, a third groove formed in the adjacent face of one of said plates, means for supplying pressure fluid to said third groove, means forming a motive fluid supply passage communicating with one of the concentric grooves on one of' said plates and with one end of the piston.

chamber', means forming a motive fluid supply passage communicating with one of the concentric .grooves on the other plate and with the opposite end of the piston chamber, and means for supplying pressure fluid constantly to the others of said concentric grooves, said valve being thrown by said constant pressure and compression pressure built up in said supply passages by said piston and in its different positions controlling pressure fluid flow through said supply passages to said piston chamber.

11. In a pressure fluid motor, a cylinder pro-` n viding a piston chamber, a piston reciprocable therein, and fluid distribution means for effecting reciprocation of said piston including a valve chest comprising cooperating abutting plates, the front face of the rear plate being circularly recessed and the rear face of the front plate forming a closure for said recess, a flat disc valve reciprocable in said recess and of a diameter less than the diameter of said recess to form a clearance about the peripheral edge of said valve, concentric grooves formed in the face of each plate and communicating with the opposite ends of said recess at the opposite sides of said valve, said concentric grooves formed on radii of the same length struck from a common center, a third annular groove formed in the rear face of said front plate on radii of greater length than said concentricvgrooves but struck from the same center, said third groove communicating near its inner peripheryrwith the exterior periphery of said recess, means forming a passage connecting one of the concentric grooves in the front plate with the rear end of the piston chamber, means forming a passage connecting one of the concentric grooves of the rear plate withY the forward end of the piston chamber, and

means' forming passages Vfor supplying pressure uid constantly to the others of said concentric grooves, said valve being thrown by the constant pressure in said other concentric grooves and compression pressure built up by the piston in said supply passages, said valve when in one position permitting uid flow from said third groove through the valve chamber past the forward face of the valve through the communicating concentric groove and supply passage to` 

